A Promise to Keep
by TrippNessa
Summary: It began with a promise - an agreement made between two rivals that no matter what happened, and no matter who won, this single vow would never be broken. How far will they go to honor it? ZaDr.


**A Promise to Keep**, Part 1: Prologue

Summary: It began with a promise - an agreement made between two rivals that no matter what happened, and no matter who won, this single vow would never be broken. How far will they go to honor it? ZaDr.

Pairings: Zim x Dib

Setting: Post series, 10 years (2 years in prologue)

Genre: Drama, Action, Romance

Rating: Mature (Swearing, Violence, Sexuality, Xenophilia)

Beta Readers: Vertorm

Author's Note: This fic takes the cancelled episodes into account, especially Mopiness of Doom, 10 Minutes to Doom and The Trial. If you aren't familiar with them, then I'd be more than happy to lead you in the right direction. Also, this is your one and only warning that this story _is NOT fluff_. There will be many sad and upsetting moments throughout this fic. _But_, there will also be many uplifting ones too, and I can promise you that the ultimate ending of this story will be a very happy one. Lastly, in regards to ages, two years passed in the show according to the Jhonen Vasquez wiki. Dib was 11 when the show began and 13 by the time it ended. Gaz was 10-12, and Zim 159-161 (15-16 Irk years, because also according to the wiki, 10 Earth years is 1 Irk year).

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><p><em>Post series, 2 years - Dib is 15, Gaz 14 and Zim 163 (16 Irk years)<em>

The sound of a giant robot crashing against the ground rang out into the night, the once peaceful bliss of sleep now lost to those nearby. Angry curses mingled with energy pistol gunshots, and the furious padding of shoes against cement quickly followed. However, no one bothered rising from their beds. Instead they simply placed a pillow over their heads in hopes of muffling it all out. It's not like this was anything new, and even if it were, they wouldn't have cared anyway.

There was a terrible sound of metal crunching and ripping. Dogs barked and cats ran from the scene as a car alarm began shrieking, its frame quite thoroughly crushed under the weight of something very large.

"Curse you, Dib!" Zim's verbal spat echoed between the buildings as he ran down the street, his Irken uniform tight against his skin as he escaped the wreckage of his once-giant robot. He had his gun pointed behind him and his head was turned around just enough to see where he was aiming. He had his antennas pointed forward though, his wig having fallen off a ways back. Dib recognized the tactic immediately; Zim was using them to warn himself of anything he might be about to run into, so that he could keep focusing his eyes behind him.

Cheating alien.

"Curse _me_?!" Dib exclaimed and shot at Zim from a couple yards back, the energy bolt just barely missing its target. The bottom of his trench coat flew along behind him, which he'd hastily thrown over his blue and white striped pajamas. "You're the one who attacked my house in the middle of the night!"

"Do you have any idea in that mushy brain of yours just how expensive that robot was?!" Zim barked and shot at Dib again. He would have hit him square in the chest had Dib not leapt to the side just in time.

"Nope!" Dib hollered back, quickly closing the distance between them as they ran. "And I really don't care either!"

Zim hissed, his serpentine tongue flicking out of his mouth in irritation. Suddenly his left antenna twitched as he approached a tall building. He quickly pulled out his PAK legs and leapt into the air, pulling himself upward along the side of it.

Dib quickly reached his left hand into one of the many hidden pockets of his trench coat and pulled out his Scaler Gun. It was noticeably larger than the energy pistol, though still able to be wielded with one hand. He pointed it up at the roof of the office building that Zim was climbing and pulled the trigger. A cord shot out, attaching itself firmly to the top of the wall. With another push of a button he was sailing upward. He then aimed the energy pistol in his right hand as steadily as he could, and began shooting.

Zim leapt from side to side with his PAK legs, each blast from Dib's gun blowing off large chunks of the building and causing debris to fall to the ground below. Dib made sure not to shoot if Zim was directly above him for that very reason, and unfortunately, Zim seemed to realize why. He stayed just above him until he was able to leap onto the roof, now out of sight.

Dib prepared himself. Zim would be ready for his approach over the top, but he had another plan. He quickly pushed a button on the Scaler and the cord stopped retracting, his body hanging still against the side of the building, just below the roof's edge. He waited a moment and then pointed the energy pistol toward the large MacMeaties billboard nearby, shooting at it three times.

If this worked then Zim's attention would be over there now, and he could pull himself onto the roof without being shot at. So, as quickly as he could, Dib hoisted himself up and over the edge with his arms. He rolled forward into a somersault and quickly pointed his guns forward once he was back up on his feet.

Zim was nowhere to be found.

Dib's body didn't even have a chance to tense before something slammed against it from behind. It only took him a second to realize that it was Zim, who was now holding Dib's arms down against his sides. The alien's chest was pressed tightly against his back, his arms wrapped around Dib's torso in a tight hold.

"Well, well..." Zim hissed with dark mirth into his ear, causing a shiver to run down Dib's spine and his heart to race in his chest. Zim was the same height as him, which only made him that much more intimidating. "Just as predictable as ever, I see."

Dib threw his head backward and smacked it into Zim's face, wincing at the pain. Zim gasped and his arms loosened just enough for Dib to pull free. He shot the Scaler at a tree in the distance, and once it had connected he pressed the retract button. Zim lunged just in time to grab onto Dib's waist, and the two of them were yanked forward.

Zim reached his PAK legs out at anything nearby, whatever he could grasp onto as they flew toward the tree. Dib wrenched and twisted in Zim's grasp, but couldn't quite shake him off. He couldn't shoot at him either, because Zim had managed to grasp his right arm during the struggle, keeping it pointed away from him. After a few more seconds of struggling and Zim failing at grabbing onto anything, they collided into the tree with a painful 'thud.'

Dib let go of the Scaler and it clattered toward the ground along with him. As he fell, he reached his left arm out desperately toward the branches. His fingers slipped off the wood and his body slid painfully down their length. He could see Zim at the top of the tree, having grasped onto it with his PAK legs easily enough. About halfway down he felt a larger branch run along his hand and he clenched down on it hard, finally stopping his fall and hanging in the air.

Dib looked up at Zim, who was climbing down toward him fast like a spider converging on its prey. He lifted his right arm up, energy pistol still held firmly in his primary hand, found the red, malicious glint of Zim's eyes, and shot.

Zim gasped and he tried to leap away, but wasn't quite fast enough, and the energy bolt hit him square in the face. There was a shriek of pain and his PAK legs let go of the branches. Dib's eyes widened as Zim fell straight toward him, and for a split second he thought to point his left hand toward something in hopes of using the Scaler to pull himself away. However, he'd dropped that gun so that he could grab onto a branch instead, and now had no way of escaping in time.

Tree branches snapped, metal PAK legs slammed against wood and dirt, and pained moans filled the space around them.

Dib blinked his eyes open and found the sky above him. Apparently he'd rolled away from the tree a bit, which was off to his left and in the middle of a field. His energy pistol was on the ground just beside his head, and his Scaler was somewhere at the base of the tree. To the right was an empty playground, and further off he could see the Skool. Right beside him was Zim, who's PAK legs were all bent up or snapped off entirely from the fall. He was lying on his side, facing Dib.

A few moments of silence passed, both of them winded and bruised, until...

"Dick," Dib's single word held no anger, sounding more like a simple statement.

"Zim is no filthy reproductive organ!"

Dib looked over at Zim, and when he saw the dramatically serious expression on his face, he burst into laughter. His mirth echoed loudly into the night, and only a few seconds later, it was joined by another. Zim's laugh was not evil; it held no malice or hidden intentions. It was genuine, and it was a sound that Dib had not heard many times before.

Time passed, the two of them just giggling and laughing at their ridiculous situation. Really it was more Dib's fault, since he'd been the one to blast Zim in the face while he was hanging precariously above him. But then again, Zim had started it in the first place. Coming straight to his house with a giant robot while he was asleep... What a jerk! Not that it had been difficult for Dib to ruin it; Zim's ideas never were. But lately, Dib had noticed a big difference in the alien's plans compared to when he'd first landed.

It used to be that Zim would attack the Earth and Dib would come to the rescue, guns and bravado blazing. Now days, however, Zim took the fight straight to him. Often times his plans would include some sort of mass-Earth-destruction scheme as well, but he always made sure to pick a fight with Dib directly. It had been this way for a while now, though he wasn't sure when it had... No, that wasn't true. He knew _exactly_ when it had begun.

Dib had never been popular or much liked at any point in his life, not even when he was very young. His interests and opinions always wound up being what others considered 'un-cool.' Somehow, through some means or another, it just _always_ ended up that way. But that never stopped him, probably because he had his father's stubbornness. He didn't care what anyone thought of him, even if it meant he'd never have any friends. The only thing he cared about was proving that the paranormal was real, and that he wasn't crazy. Someday... _someday_ he'd show them all.

But like anything that stands tall against a violent storm, there would eventually be chips and cracks in the wall. The armor would start to rust, the tree would start to bend, and the small boy who had been picked on his entire life would finally give in to the desires of others. And Dib did.

He'd announced his resignation as Zim's nemesis to the alien first, having decided to give up on studying the paranormal and defending the Earth. Of course Zim had cackled manically in response, but Dib knew it was what he needed to do. If Zim won because of it, then at least he'd die having finally been someone. His father would respect him as an accomplished scientist, and no more would he have to get beaten up by a psychotic alien just because he tried to protect the very assholes that had made his life miserable since day one. He didn't care what happened to them anymore, he _hated_ them, and he was going to become something _better_.

His father had been proud, and for the first time in Dib's entire life, he'd seen him almost every day. They'd worked together on many fantastic science projects and discoveries, and Dib had even been in the news a few times. It was everything he'd ever wanted...

And yet, this time around, the wall crumbled to the ground, the armor rusted all the way through, and the trees fell over completely. Dib was faced with a harsher storm, one that left him feeling worse than ever before. Being picked on, beaten up, losing to Zim, fighting for people he didn't care about, being told he was crazy because he_ really did fucking see Big Foot_... Those problems were nothing in comparison to the sheer loneliness he felt while working with his father. The empty hole that had been ripped through his heart was more painful than any bully or invalidation had ever been; he'd failed his purpose. His basic principle in life, to defend the Earth from evil no matter the cost, and to prove that the paranormal things he'd_ seen with his own eyes_ were real... that was who Dib _was_. Yes, it was certainly a hard path to walk at times. He'd found himself beaten and bruised from it far more times than he could count. But it was the path that was true to him, and he'd wandered away from it, down into an empty, barren wasteland instead.

Dib had raced to Zim's house as quickly as he could and thrown open the front door. He probably should have realized that something was up from the fact that the gnomes didn't attack him, but he'd been too focused on other things. What terrible schemes had his enemy created without him around to put a stop to them? As it turned out... there weren't any.

He'd found Zim just sitting on his couch, staring at the TV with magazines strewn all over the floor and his house in complete, disgusting disarray. At first Dib was too surprised and confused to say anything, but he'd quickly realized that all of those magazines, and even the TV reports, were about him. Dib Membrane and his father, two scientists and their achievements. It seemed that Zim had also been left purposeless and empty from Dib's change of pace, and the evidence was plain to see.

So Dib did the only thing he could, and loudly proclaimed himself as Zim's nemesis once again, swearing that he'd expose him as the evil alien menace that he was. Zim's eyes, once empty and glazed over, were almost immediately filled with life again. And just like that, everything had gone back to normal... Except for one very important difference.

Never again had Dib seen true hatred in Zim's face when they fought or argued. Even in the middle of some of their worst moments, all Dib could find in those red eyes was competition and excitement. And if he were being completely honest with himself, he knew it was the same for him. The thrill of the fight, the love of the game... It was the result of realizing that neither of them had much else going for them on this tiny, spitball of a planet. Without each other, there was nothing to look forward to. Dib would no longer have that feisty alien to test his skills against, and Zim would no longer have that defiant human keeping his mission challenging.

It was that very line of thinking that caused Dib to ask a question that would change their lives forever.

"Hey, Zim?" Dib's voice was quiet after they'd finally finished laughing, both looking up at the starry night sky.

"Hmm?" Zim's response was equally quiet, though he did not move to look at him.

"Are you really going to destroy the Earth?"

Zim frowned a bit, which Dib caught from the corner of his eye. Zim seemed to think for a moment, a heavy silence falling between them. Eventually his expression softened though, and Dib knew that he understood what he'd truly been asking. More than wondering about the fate of the Earth, Dib had been inquiring about _them_. After everything that had happened, everything that they'd learned, had their relationship really not changed at all? Were they still just enemies, even when they had come to realize that their lives would be meaningless without the other?

"My mission is the same, Dib," Zim's voice was low, emphasizing its seriousness. "I will not fail or give up on it, not even for you."

Dib felt his eyes soften in sadness. He'd fully expected that answer, though there was still a part of him that hurt to hear it. Maybe he'd hoped too much that somehow they could just... _just_... "Then will you make me a promise?" Dib eventually asked. "From one rival to another?"

At the edge of Dib's vision he saw Zim's lips curl up into a grin; never before had one of them described their relationship as a rivalry. They had always been each other's nemesis or enemy. The difference, however, was that rivals did not hate each other, they just had such opposing purposes and goals that they constantly fought one another. That felt more accurate now, because Dib didn't hate Zim, and he knew that Zim didn't hate him. They could never be friends or allies though, because that meant letting go of the thing that meant the most to them. Zim would never give up on his mission, and Dib would never let him succeed at it. So that left them with their rivalry, and the bitter knowledge that in another life, under different circumstances, maybe things could have been different.

But this wasn't another life, this was here and now, and in this life there were no compromises to be found between them.

"What promise?" Zim asked, still looking upward.

"I never want to live in a universe where the Earth is gone and I'm still alive," Dib began, his eyes glazing over with emotions. "That means I failed and have nothing left. And I never want to watch my own planet burn or be enslaved... so promise me that you won't call the Armada or destroy the Earth unless you've killed me first."

Zim was quiet. He hadn't moved his head, so Dib continued to stare at the sky, waiting patiently for his response. Maybe he was asking too much and Zim would refuse, but he had to ask anyway. He had to _try_. From one rival to another, maybe, just maybe, they could have this one agreement.

After a strangely comfortable silence, and not a short one either, Zim finally spoke, "In return, will you promise to never allow me to be cut open alive?" Zim's voice was very serious. "If you ever deliver me to one of your nasty research groups, will you swear to only give them a corpse?"

Dib finally looked at Zim, and Zim looked back at him. After a moment Dib smiled and nodded, deciding that he'd be willing to promise just about anything to have the reassurance of never seeing his home destroyed. He'd have to already be dead, and then it wouldn't matter anymore.

Zim smiled as well, and they both looked back up at the stars together in silence. It wasn't a full compromise, but it was a start. They'd made an agreement out of their strange respect for one another, and maybe someday, somehow, there could be more. But this was today. Tomorrow things would go back to normal, and they'd be fighting again.

So they stayed there for many hours, just the two of them and their promise.


End file.
